1989 xr4 150 that sat 3 years issues.

[Faztbullet]

Oiling is way different on 4 stoke car HiPerf vs 2 stroke..I will see if I dig out a old coated piston

 

[Lt1z350]

Teflon coating only for break-in ...its gone in about 3 hours running. just about every puts the black coating on

Yea well seems it’s useless like you said on the boat motors and not like automotive as I called them.
I can’t even get a spec for piston to wall clearance. Or recommended hone grit for the rings they are using. I cleaned it up with a 220 grit hone and am at 3.379 at the largest cylinder. Would be nice to know a spec for it but they won’t give anything like a good piston manufacturer will. I probably didn’t take .002 from it as they cleaned up pretty quick with out a lot of time on each hole. I hate to spend Weisco type money on it just to get a piston to wall spec and put the forged in it. But if this is too loose then will be cheaper to buy forged then pay to get the .010 bore done to it.

 

[Lt1z350]

Oiling is way different on 4 stoke car HiPerf vs 2 stroke..I will see if I dig out a old coated piston

Any chance you know factory specs for max clearance on the piston to wall? But yes your correct on the Teflon.

 

[Dukedog]

.003 for cast and .008 for forged..................

 

[Lt1z350]

.003 for cast and .008 for forged..................

Cool thank you. I have taken quite a few measurements and even getting 3.375 closer to the bottom of the bore where skirt stability matters. But near top 3.378 and that’s with a near done finish.

 

[Dukedog]

sounds like ya got what ya got and will probably do without startin' from scratch with all new holes.. might put new std. pistons in it and call it a day......... i always liked "loose" (cast or forged) with tha mercs anyway.... jmo

jan.. never had a problem with 'em either!

 

[Lt1z350]

sounds like ya got what ya got and will probably do without startin' from scratch with all new holes.. might put new std. pistons in it and call it a day......... i always liked "loose" (cast or forged) with tha mercs anyway.... jmo

jan.. never had a problem with 'em either!

So wsm also finally answered me and said their pistons are designed to go back into blocks that are honed so they are good to 3.380 so slightly larger then any oem replacement which was designed for a new engine. So either way look Iike it will be ok and if a little loose so be it. It’s also nice knowing someone purposely runs th this way so thank you.
As far as for engine temp is it better to run it stock heat range or colder as I see many like yo do so with these mercs? I have seen 147 thermostat which I assume isn’t stock
I cut the heads a little as mentioned before and was going to put the cms reeds and stuffers in it unless anyone says don’t bother. My original idle issues just worried to leave reeds as is and leave a problem on the table possibly.

 

[Dukedog]

production stats are 143's... i always liked "controlled heat" 160 ta 170.... but i didn't string my junk out for miles n miles....

 

[Faztbullet]

Slap a set of Siezcos in it as they like sloppy holes and call it a day. Just let em go thru several heat cycles to temper em up.

 

[Lt1z350]

So it’s coming along working on a few projects. Going to work on buttoning it up today and get drive ready and cleaned up. I ended up around 3.378 on most holes which these pistons I got were good to 3.380 by manufacturers specs. I used a 180 grit on final hone and I’m happy with how good it cleaned up. Pistons feel so much better as the stock rocked in the holes pretty bad. If it ran as good as it did that way I can’t imagine how well it should run now.
I read to do a couple long idle heat cycles before going out and no wot at first so will run some fuel through it and maybe even on the heavy side for oil until I get some time on it. Wife talked me into a bow rider so all this work will be for someone else enjoyment once I’m happy with how it’s running and the boat performs. Will make some one who likes to fish and haul ass happy I think. Lol